From Comic-Con comes the first gameplay video amateur Beast Mode Gears of War 3, which shows for the first time Serapede, the centipede is capable of making electrical connections, and the view of the Berserker, which is disturbed halved due to the blackout and special edges. I'll suggest below, waiting for the official video or better quality.

Gears of War 3 - Comic-Con Gameplay Serapede and Berserker